Technical Field
The present invention relates generally to memory devices and, in particular, to a resistive switching memory stack for a three-dimensional structure.
Description of the Related Art
Resistive random access memory (a.k.a. RRAM or ReRAM) is considered as a promising technology for electronic synapse devices or memristor for neuromorphic computing as well as high-density and high-speed non-volatile memory application.
In neuromorphic computing applications, a resistive memory device can be used as a connection (synapse) between a pre-neuron and post-neuron, representing the connection weight in the form of device resistance.
Multiple pre-neurons and post-neurons can be connected through a crossbar array of RRAMs, which naturally expresses a fully-connected neural network.
The density of ReRAM can be increased by vertically stacking ReRAM stacks as practiced in Flash NAND technology, however, ReRAM stacks are typically deposited by Physical Vapor Deposition (PVD) to control the oxygen vacancy concentration in the metal oxide layer and this prevents application to three-dimensional (3D) structures.
Thus, there is a need for RRAM for 3D structures.